Method for charging liquid products into pressure-tight containers



Jlily 27, 1954 D. M. Mc 2,684,806

METHOD FOR CHARGING LIQUID PRODUCTS INTO PRESSURE-TIGHT CONTAINERS Filed Feb. 2, 1952 INVENTOR 00061146 M M65154 6w ATTORNEYS Patented July 27, 1954 METHOD FOR CHARGING LIQUID PROD- UCTS INTO PRESSURE-TIGHT CON- TAINERS Douglas M. McBean, Rochester, N. Y., to Carter Products, 1210., New York,

assignor N. Y., a

corporation of Maryland Application February 2, 1952, Serial No. 269,657

Claims. 1

This invention relates to the filling of pressure-tight containers with a composition comprising a mixture of an aqueous soap solution and a volatile propellant in liquid phase, which propellant has a vapor pressure considerably above atmospheric pressure at room temperature and accordingly acts to propel the product out of the container. The propellant may also act to modify the physical state of the product as it emerges from the container, as by expanding it into a foam or lather. The present invention more particularly concerns a method of so packaging such a composition that no substantial partial pressure of air remains in the head space of the filled and closed container, whereby the pressure in such head space is substantially solely that due to the volatile propellant.

Certain liquid compositions comprising liquid products and volatile propellants have been packaged in pressure-tight containers, such as cans, equipped with outlet valves whereby the product is propelled from the can by the pressure built up therein by the propellant vapor when the outlet valve is opened. Propellants useful for this purpose necessarily have a relatively high vapor, pressure, usually ranging from about 30 to 80 or 85 pounds per square inch gauge at 70 F. A vapor pressure within this range is necessary to insure that all of the liquid product will be expelled from the can at the desired velocity under all temperatures to which the can and its contents may be subjected in use. Although high vapor pressure near or even above the upper limit indicated are desirable for effective expulsion of the product, high pressures are clearly undesirable when safety and shipping regulations are considered. Thus, if the can is made economically of light gauge metal, such as is used for ordinary canned foods and beverages, the maximum pressure developed in the can at the maximum temperature to which it is likely to be subjected must be held below a limiting value. The limiting value may be fixed by the pressure at which the can will bulge or leak or it can be fixed by shipping regulations. In any case, if the vapor pressure of the propellant is such that the maximum safe pressure is exceeded, the only alternative is to employ expensive heavy gauge metal containers.

When cans are filled with liquid product and volatile propellant, a considerable proportion of the ambient air that occupies the empty cans before filling is trapped in the head space of the can, and the vapor pressure of this air increases the head space pressure to a value above that of the vapor pressure of the volatile propellant. Evacuation of the cans prior to filling may reduce the density of the air so trapped, but complete removal of the air prior to filling cannot be economically accomplished by evacuation in com mercially practical filling operations. The air pressure is not useful in propelling the product from the can and it is undesirable in that it increases the head space pressure due to the propellant, and so requires the use of undesirably low vapor pressure propellants if dangerous or forbidden pressures or heavy and expensive containers are to be avoided.

With the above considerations in mind, it is proposed, in accordance with the present inven* tion, to provide a method of packaging composi tions that comprise essentially an aqueous soap solution and a volatile propellant, which comprises first partially filling the open topped, previously empty and air-filled can or container with an aqueous soap solution, then bubbling through this solution in the can a gas that is soluble in the soap solution or the propellant, or both, whereby the soap solution is expanded into a foam that completely fills the container to the brim and may overflow slightly, displacing all air from the container and preventing diffusion of air back into the container, and then while the foam still completely fills the container, sealing a cap onto the can to close and seal its previously open top. The filling is thereafter completed by introducing the volatile propellant in liquid phase into the container preferably through a valve in the cap, either alone or with an additional amount of aqueous soap solution. With this procedure, the head space pressure comprises substantially only the pressure of the volatile propellant, and accordingly a propellant can be used which has the maximum vapor pressure permissible in the construction of can or container being filled.

In describing the invention in detail, reference will be made to the accompanying drawing, in which the single figure illustrates in diagrammatic and simplified form one arrangement of apparatus by which the method of the invention may be carried out.

Inthe drawing, there is shown for the purpose of illustration a can or container C comprising cylindrical side wall 1, a bottom wall 2 sealed thereto and an integral top wall 3 having a central valved cap receiving opening therein. The valved cap of the illustrated can may be sealed into the can opening t by suitable attaching mechanism, such as a seamer, of known construction, diagrammatically illustrated at 5. The can 3 may be carried to the foam flushing station F and the valve attaching station V by hand or by suitable conveyors diagrammatically illustrated by the belts 32 and 35.

The valved cap assembly shown by way of illustration comprises a cap disc 5 having a valve tube extending through and sealed in a central opening therein. The tube 'i has an inturned flange 8 at its inner end which forms a valve seat for cooperation with a valve plug 9 carried by a stem ill extending through the tube '5. The stem iii is biased to move to the valve closing position by a spring 1 l compressed between the inner face of the flange 8 and a stop it struck from the stem Hi. A syphon tube it may be fitted over the inner end of the valve tube '4 and extends to a point near the bottom of the can to insure substantially complete expulsion of the can contents when the can is in a substantially vertical or slightly tilted position.

The empty open topped can is preferably first partially filled with aqueous soap solution at the soap filling station S. The amount of such soap solution there introduced into the can may comprise the entire soap solution charge desired in the completely filled can or it may comprise less than such entire charge. In either case, a considerable head space is left in the can, as is shown at station 8. The soap solution may be introduced into the can from a suitable reservoir, not shown, through a valved pipe 23.

The volatile propellant in liquid phase and in some cases an additional amount of aqueous soap solution is introduced into the can at the filling station L. The can is sealed in a gas-tight connection with the filling conduit during the operation of introducing the volatile propellant in liquid phase and, when required, the additional charge of aqueous soap solution. Various forms of apparatus may be used at the filling station as L, and that here illustrated is similar to the apparatus disclosed in detail in my copending application Serial No. 147,588, filed March i, 1950, entitled Apparatus for Charging a Liquid Product and a Volatile Propellant into a Pressure Container.

As shown, the filling mechanism includes a block Hi having a valve chamber iii therein communicating with a filling opening it, the downwardly disposed mouth of which is surrounded by a sealing gasket ll shaped to engage and form a tight seal with the valve tube of a can C when the can is lifted into contact therewith by a platform lift it of suitable construction.

A valve operating rod 59 is centrally secured in the filling opening it of the block it so as to engage the valve stem is and so open the can valve when the can is lifted to the filling position, as shown.

A piston valve 26 is slidably disposed in the valve chamber l5. In its lower position as shown, the piston valve closes the conduit 26 leading from the propellant conduit 22 and the soap solution product conduit 25. In its raised position, the piston valve Zil connects the propellant conduit 22 and the soap solution product conduit 2% to the filling opening it. Suitable valves 2? and 28, here shown as manually operable valves, are provided to respectively control the propellant and soap solution product conduits 22 and 25. The propellant conduit 22 is connected to the propellant cylinder 34 of a propella-nt metering device, generally designated P and comprising essentially a power cylinder 35 carrying a piston 36 connected by a rod 3! to a piston 38 in the propellant cylinder 34. Compressed air or other motive fluid from a suitable source is alternately admitted to and vented from opposite ends of the power cylinder under control of the valves 39 and ii) in order to reciprocate the connected pistons 35 and 38 and so force successive measured charges of propellant from the cylinder 34 and into the successive cans to be filled. Volatile propellant in liquid phase is supplied to the propellant cylinder 34 from a supply tank 4| through a conduit 32 including a check valve 43.

The soap solution product metering device S is also of double cylinder construction and includes a cylinder M connected to the conduit 25 and to a product supply tank 35 through a conduit 46 including a check valve Al. A piston 48 in the cylinder 44 is connected by a rod 49 to a power cylinder piston 50. Compressed air or other motive fluid is admitted to and vented from the power cylinder 5| by means of a valve 52, whereby the connected pistons are reciprocated to deliver successive measured charges of aqueous soap solution to the successive cans to be filled. In operating the apparatus described, a can C is lifted into sealed contact with the gasket ll around the filling opening 56 and at the same time its valve stem it is depressed to open the can valve. The filling apparatus is then operated by a suitable manipulation of the described valves to supply a measured quantity of volatile propellant in liquid phase to the can, thus raising the pressure in the can to a pressure considerably above atmospheric pressure, a portion of the filled volatile propellant vaporizing and occupying the head space of the can. When necessary or desirable, a small charge of the aqueous soap solution is added before, after or simultaneously with the volatile propellant in liquid phase. The pressures under which the propellant is introduced into the can are maintained at high superatmospheric values considerably above the vapor pressure of the volatile propellant at the prevailing temperature, so that the charging operation is rapid and no substantial vaporization of the propellant occurs during charging. After charging, the can C is lowered and its valve closes.

In accordance with the present invention, there is provided at the flushing station F a suitable duct for introducing the soluble foaming and flushing gas to expand the initially introduced soap solution and so displace the ambient air from the head space of the can. As shown, there is provided a tube or nozzle 53 connected by a flexible conduit fi l with a cylinder or tank 55 containing the gas under pressure. A valve 56 adjacent the nozzle 53 controls the flow of gas therefrom. After partial filling of the can with aqueous soap solution at station S, and before the valved cap is secured in the top opening 4 of the can, the nozzle 53 is introduced through the can opening l, with its open end below the soap solution liquid level and preferably near the bottom of the can as shown, the valve 56 is opened, and a stream of gas is introduced into and bubbled up through the aqueous soap solution. The gas expands the aqueous soap solution into a foam or mass of bubbles and so quickly raises the level of the material in the can to its open top, whereupon the valve 56 is closed and the nozzle 53 is withdrawn from the can. It is preferable in some cases to continue the introduction of gas until the soap solution foam slightly overflows the top of the can before the gas is shut off and the nozzle withdrawn. This overflowin causes any air bubbles 32 that may have been lying on the surface of the soap solution prior to gas introduction to flow out of the can. The foamed soap solution completely displaces the ambient air from the can. The gas is preferably introduced from a tank 55 of liquid carbon dioxide, nitrous oxide or like soluble gas, and the tank valve 33 is preferably so adjusted that the pressure under which the gas is introduced is low so that the soap solution is not blown out of the can. A gas pressure at the opening of the nozzle 53 of about three to six inches of water is suitable.

The soap solution remains as an expanded foam, completely filling the can and usually bulging slightly from its open top 4 for an interval of from one to five minutes. Before the end of this interval, the valve cap is applied to and sealed on the can by means of the seamer 5. The can is thus sealed with substantially no air in it. After the valved cap is sealed to the can opening ii, the can is transferred to the filling station L and the volatile propellant in liquid phase is introduced to the can through the can valve, as described above. In the event less than the entire charge of aqueous soap solution was initially introduced at the station S prior to foam flushing, an additional amount of soap solution sumcient to make up the deficiency is introduced before, after or at the same time as the volatile propellant is introduced at the station L. After complete filling, the can is lowered, its valve closes, and the filling operation is complete.

The method of the invention may be employed with advantage in the filling of compositions comprising soap solutions with propellants that are relatively insoluble in the soap solution products. Examples of such compositions are those comprising aqueous solutions or suspensions of soap, synthetic detergents or other water-soluble or suspendable materials, and volatile propellants that are relatively insoluble in water or aqueous solutions. Such propellants include one or a mixture of one or more of the substantially water insoluble saturated aliphatic partially fluorine substituted hydrocarbons and the saturated aliphatic partially and wholly chlorine and fluorine substituted hydrocarbons, and particularly those in which all of the hydrogen atoms are replaced by chlorine and fluorine and in which the number of fluorine atoms in the molecule equals or exceeds the number of chlorine atoms. Examples of such propellants are dichlorolifluormethane (CC12F2), 1,2, dichlor 1,1,2,2 tetrailuorethane (CClF2.CClFz), trichlortrifiuorethane (CzClsFs), 1,1 difluorethane (CI-I3.CHF2), monochlordifluormethane (CHClFz), monofluortrichlormethane (CFCls), 1,1 difluorethane (CH3.CHF2) and 1 monochlor 1,1 difluorethane (CC1F2.CH3). Aqueous product and volatile propellant compositions of this type are disclosed in detail in copending application Serial No. 125,032, filed November 2, 1949, now Patent No. 2,655,480, issued Jan. 23, 1953, and entitled Lather Producing Composition and Method.

When packaging compositions of the type above identified, the flushing foam producing gas preferably comprises a compound that is readily soluble in water or aqueous solutions or in the propellant. Carbon dioxide and nitrous oxide are preferable because they are relatively inert, inexpensive and substantially odorless. Ethyl chloride, methyl chloride and b-butane may also be used. When the aqueous product is slightly alkaline, as may be the case with ordinar soap solutions, carbon dioxide is particularly effective because it is readily soluble in alkaline solutions. If the aqueous soap solution is neutral, nitrous oxide is preferable to carbon dioxide as the flushing gas. The preferred flushing foam producing gas is the propellant that is used to propel the soap solution from the container, since this gas is, of course, completely soluble in the propellant that is subsequently introduced. Examples of such gases are disclosed above. When the flushing foam producing gas thus comprises the volatile propellant in vapor phase, the residue of the gas that produces the foam which remains in the container after sealing is either dissolved in the subsequently filled propellant in liquid phase or remains as a part of the head space vapor, or both, but this residue does not increase the head space pressure above the vapor pressure of the volatile propellant in liquid phase that is subsequently introduced.

After sealing of the can, the flushing foam producing gas dissolves in the aqueous soap solution or in the propellant or in both. If introduction of the volatile propellant is delayed for a sufficient period after sealing, the foam in the can subsides, leaving a head space which is under substantially complete vacuum. Due to the dissolving of the flushing foam producing gas, the pressure in the head space of the filled can is substantially solely that due to the vaporized propellant, and accordingly does not substantially exceed the vapor pressure of the propellant at the prevailing temperature.

I claim:

1. The method of packaging in a pressuretight container, a composition comprising a soap solution and a volatile propellant in liquid phase which comprises first introducing into the container at least a part of the desired charge of soap solution unmixed with gas, then passing through the soap solution so charged from a point substantially beneath the liquid level of the soap solution a gas that is soluble in at least one of the soap solution and the volatile propellant, the gas pressure at the point of introduction being not substantially greater than sixinches of Water, until the soap solution is expanded into a foam that completely fills the container, closing the container and then introducing the volatile propellant in liquid phase into the container.

2. The method claimed in claim 1, in which the gas passed through the soap solution is carbon dioxide.

3. The method claimed in claim 1, in which the gas passed through the soap solution is nitrous oxide.

4. The method claimed in claim 1, in which the gas passed through the soap solution is ethyl chloride.

5. The method claimed in claim 1, in which the gas passed through the soap solution is methyl chloride.

6. The method of packaging in a pressure-tight container, a composition comprising a soap solution and a volatile propellant in liquid phase which comprises first introducing into the container at least a part of the desired charge of soap solution unmixed with propellant, then bubbling the volatile propellant in vapor phase at a pressure not substantially exceeding six inches of water through the soap solution so introduced until such soap solution expands into a foam that completely fills the container, closing the container with a valved closure and then introducing through such valved closure the volatile propellant in liquid phase.

'7. The method of packaging in a pressure-tight container, a composition comprising a soap solution and a volatile propellant in liquid phase which comprises first introducing into the container a part of the desired charge of soap solution unmixed with propellant, then bubbling the volatile propellant in vapor phase at a pressure not substantially exceeding six inches of water through the soap solution so introduced until such soap solution expands into a foam that completely fills the container, closing the container with a valved closure and then introducing through such valved closure the volatile propellant in liquid phase and the remainder of the soap solution to be charged.

8. The method of packaging in a pressure-tight container a composition comprising a charge of an aqueous soap solution and a volatile propellant in liquid phase comprising at least one compound selected from the group consisting of the saturated aliphatic partially fluorine substituted hydrocarbons and the saturated aliphatic partially and wholly chlorine and fluorine substituted hydrocarbons, which comprises first introducing into an open-topped container at least a part of the charge of soap solution unmixed with propellant, then passing through the soap solution so introduced from a point substantially below the liquid level thereof the volatile propel lant in vapor phase at a pressure not substantially exceeding six inches of water until the soap solution is expanded into a foam that completely fills the container and displaces air therefrom, closing the container and then introducing the volatile propellant in liquid phase into the closed container.

9. The method of packaging in a pressure-tight container a composition comprising a charge of an aqueous soap solution and a volatile propellant in liquid phase comprising at least one compound selected from the group consisting of 1,2 dichlor 1,1,2,2 tetrafluorethane, trichlortrifiuorethane and dichlordifluormethane, which comprises first introducing into an open-topped container at least a part of the charge of soap solution unmixed with propellant, then passing through the soap solution so introduced from a point substantially below the liquid level thereof the volatile propellant in vapor phase at a pressure not substantially exceeding six inches of water until the soap solution is expanded into a foam that completely fills the container and displaces air therefrom, closing the container and then introducing the volatile propellant in liquid phase into the closed container.

10. The method of packaging in a pressuretight container a composition comprising a charge of an aqueous soap solution and a volatile propellant comprising dichlordifluormethane which comprises first introducing into an open-topped container at least a part of the charge of soap solution unmixed with propellant, then passing through the soap solution so introduced from a point substantially below the liquid level thereof the volatile propellant in vapor phase at a pressure not substantially exceeding six inches of water until the soap solution is expanded into a foam that completely fills the container and displaces air therefrom, closing the container and then introducing the volatile propellant in liquid phase into the closed container.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 981,768 Ketterer Jan. 1'7, 1911 2,114,964 MacKenzie Apr. 19, 1933 2,338,108 Gartland Jan. 4, 194 2,372,457 Stewart Mar. 27, 1945 2,518,064 Rapisarda Aug, 8, 1950 

